Fitness

Definition

Fitness, in an evolutionary context, refers to the ability of an organism to survive and reproduce in its environment. It is often measured by the number of offspring an individual produces that survive to reproductive age. Higher fitness indicates a greater likelihood that an organism's traits will be passed on to the next generation, playing a crucial role in natural selection.

5 Must Know Facts For Your Next Test

1. Fitness is not just about physical strength; it encompasses all traits that contribute to survival and reproduction, including behavioral and physiological adaptations.
2. The concept of fitness is relative; an organism's fitness is often compared to others in the same population or environment.
3. Environmental changes can alter what constitutes high fitness, meaning that traits advantageous in one context may become detrimental in another.
4. Fitness can be influenced by various factors including food availability, predation pressures, and competition for resources.
5. Evolutionary changes over generations are driven by differences in fitness among individuals, shaping the genetic makeup of populations.

Review Questions

• How does the concept of fitness relate to natural selection and adaptation within a population?
  • Fitness is a key component of natural selection, as it determines which individuals are more likely to survive and reproduce in their environment. Those with higher fitness possess traits that enhance their chances of survival and successful reproduction. Over time, these advantageous traits become more common in the population through adaptation, as individuals with lower fitness may not pass on their genes as effectively.
• In what ways can environmental factors influence the fitness of an organism, and how might this impact evolutionary processes?
  • Environmental factors such as climate, availability of resources, and presence of predators can significantly impact an organism's fitness. For example, a drought might decrease the availability of food for a species, reducing its overall reproductive success. Such changes can drive evolutionary processes by selecting for traits that improve survival under new conditions, ultimately leading to adaptations that shape future generations.
• Evaluate how changes in fitness can affect genetic diversity within a population over time and what implications this has for evolution.
  • Changes in fitness can lead to shifts in genetic diversity within a population by influencing which traits are favored under certain environmental conditions. When specific traits enhance fitness, those genes become more prevalent as individuals with those traits reproduce more successfully. Conversely, if a trait reduces fitness, it may diminish in frequency. This dynamic can either increase or decrease genetic diversity depending on whether advantageous mutations arise or if selective pressures lead to a loss of variation, which has significant implications for the population's ability to adapt to future environmental changes.

Related terms

natural selection: The process by which organisms better adapted to their environment tend to survive and produce more offspring.

adaptation: A trait that increases an organism's fitness and is the result of the evolutionary process.

reproductive success: The measure of the number of offspring an organism contributes to the next generation, directly related to its fitness.